Port Scan

Scan common TCP ports on a host or IP address.

Computers talk to each other through "ports" — numbered doors, each usually assigned to a specific kind of service (port 443 for secure websites, 22 for SSH, 25 for email, etc.). This tool checks which of the common ports are open on a host or IP, from outside. Useful to see what services a server is exposing, or to verify your own server is reachable.

What "open" actually means

Open — there's a service answering at that port. For example, port 443 open means the host runs a web server (HTTPS).
Closed / not shown — nothing is listening, or a firewall is blocking the probe. From outside, the two look similar.
The port number itself only suggests what type of service is there. The actual program could be anything; ports are conventions, not enforcement.

When you'd use this

Setting up a server at home — confirm port 80 / 443 is reachable from outside, not just from inside your network.
Checking what a public server exposes — see which services a hosting provider, smart device, or router is offering to the internet.
Spotting security issues — services like SSH (22), databases (3306, 5432, 6379, 27017), or admin panels (Telnet 23, RDP 3389) usually shouldn't be visible from the public internet.

Please only scan your own systems

Scanning a server you don't own — even just for curiosity — may be against that server's terms of service and, in some places, against the law. This tool is for checking systems you operate or have explicit permission to test.